Adaptable wastewater treatment systems

HiPAF® midi and modular is for properties from 60 up to 2,000 population equivalent (PE) where mains drainage is unavailable.

Our wastewater treatment systems are adapted to meet your specific needs, backed by continued dedicated technical support throughout the whole project.

  • Meeting Environment Agency standards even at sensitive sites
  • Resilient process managing seasonal variations in occupancy levels
  • 25 years design life that are simple to install, operate and maintain
  • Future proof – to scale operations as treatment demands grow
  • Hire solutions to keep sites operational and within consent

 Image of a below ground WPL HiPAF® midi package wastewater treatment plant for off mains drainage treating populations up to 300 PE 


Why you should choose the HiPAF:

Low maintenance and long term reliability

  • No internal mechanical or electrical moving parts within the tank
  • Remote monitoring available
  • Emptying of the tank not required during maintenance – simply isolate and remove sections of the air distribution system
  • Tankering made easier because primary sludge and humus are stored together
  • Lockable large gas strut lids for safe access
  • Low energy compressors with adjustable timers available
  • Variable speed drive blowers to optimise power use available

Ease of installation

  • Small footprint size
  • Modular design allows ease of access in and on to restricted sites
  • Off-site build reduces installation time and cost

Robust process

  • Rectangular shape of the midi and modular plants reduces dead zones
  • Use of high quality blowers and pumps underpins reliability of the plant
  • No odours – most other treatment plants have a separate primary tank which store settled solids and can emit odours; however our plant has no separate primary tank and is therefore odour-free
  • Glass reinforced plastic (GRP) is UV stabilised with an external gel coat finish which extends the asset life to 25 years

Variable flows and loads

  • Unique design of the flow balancing in the primary tank means it can cope with variable flows and loads making it idea for caravan sites and other seasonal venues

Our discreet packaged plants can be design engineered to operate efficiently based on seasonal variations in loadings often experienced by hotels, caravan parks and cafés. Higher pollution loads and site expansion can be accommodated by adding treatment modules

Minimal visual impact

  • Below ground installation means the plant does not impede views of the landscape
  • Discreet for use in tourist and leisure applications


  • Fully compliant with UK Building Regulations and Environment Agency guidelines
  • WCS Environmental Engineering uses British Water’s Code of Practice – Flows & Loads
  • The midi and modular options are designed in accordance with BS EN 12255-1/15 and manufactured using BS 4994 as a guide.
  • Meets all current legislation under the Environmental Permitting Programme

With unrivalled specialist capabilities, we supply technical information and drawings; offering any additional assistance if required. This is to ensure a wastewater treatment solution that works effectively and efficiently, with minimal impact on the day to day running of businesses.

Sites of Special Scientific Interest (SSSI)

The WPL HiPAF uses no chemicals during the treatment process and will safely discharge wastewater in to the local environment where extra consideration is needed for locations such as a burn, nature reserve, fisheries, salmon river or close proximity to water extraction (well). This makes our products the preferred choice for sensitive locations such as Sites of Special Scientific Interest (SSSI).

Technical specification

For technical specification information (including indicative drawing), please download  the WPL HiPAF brochure (available on this page).


  • The kiosk is acoustically-lined, houses a control panel, which automatically manages the operation of the plant; the air distribution manifold and one or more air blowers as required
  • Thermostatic cut-off controls and air filtering monitoring which can alert the operator to loss of air pressure
  • Ten metres of high temperature resistant airline hose is supplied to connect blowers to the treatment plant – extra lengths can be supplied if the kiosk is sited further than 10m from the treatment unit

Image of WPL Midi compact sewage system installed at McDonalds

Typical commercial uses:

  • Animal waste options such as stables and kennels
  • Agricultural growers and garden centres
  • Caravan and camping, lodges and residential parks
  • Custodial establishments
  • Golf courses, fishing lodges and yacht clubs
  • Hotels, restaurants and public houses
  • Housing developments
  • Motorway service stations
  • Manufacturing – industrial trade effluent
  • Care homes and retirement villages
  • Commercial buildings and offices
  • Schools, colleges and training centres
  • Stately homes and large country estates
  • Villages and rural communities
  • Visitor centres
  • Zoos, theme parks and leisure attractions and leisure centres
  • For water utilities requirement, please see WPL HiPAF® bespoke systems

Three stage system for safer processing

Each WPL HiPAF treatment plant includes a three-stage process – primary settlement, biological treatment (biozone) and final settlement. The segmented biozone process chambers in stage two eliminate the risk of process short-cuts and mitigates risks associated with variable loads.


Stage 1 – Primary settlement

  • Incoming wastewater enters the primary settlement stage where organic and inorganic matter settles
  • The sludge is held in this section until it requires de-sludging
  • A unique forward-feed arrangement uses an airlift to deposit wastewater into the biological treatment stage (biozone), which keeps peak flows from entering the system and prevents hydraulic surges

Stage 2 – Biological treatment

  • Settled liquor enters the biological section either by displacement or via the airlift
  • High-voidage plastic media, contained between two floors within the biozone, encourages the growth of bacteria and other organisms which treat the wastewater
  • Air required for the treatment process is delivered by air-blowers housed in a weatherproof kiosk
  • The air also helps to scour the media bed, preventing the filter from blocking
  • A series of diffusers installed beneath the media bed ensure an even distribution of air

Stage 3 – Final settlement

  • The treated wastewater (final effluent) enters the final settlement section
  • Dead biomass (humus sludge) from the process settles out
  • An airlift automatically transfers settled humus sludge back to the primary settlement section for co-settlement
  • The final effluent is discharged through gravity displacement to either a watercourse or a sub-surface irrigation field

Footage of a WPL HiPAF wastewater  treatment system (620 PE) in the Czech Republic which has cut costs, allowing for greater investment in site landscaping and design. The high environmental standards required included 22mg/l biological oxygen demand (BOD), 25mg/l suspended solids and 12mg/l ammonia. Phosphate removal was also specified by the environmental regulator.

Discover more: Innovative installation cuts cost of Czech wastewater treatme